Yep, ultimately fossil fuels are finite resources.
Oil and gas do seem to be really quite limited relative to present use of them. If it wasn't for that, if supplies were plentiful, then the industry wouldn't go into deep water, physically hostile environments and war zones in order to gain access. If there were vast resources elsewhere then it'd be a pretty impressive conspiracy to have kept them hidden so long.
Coal there's a lot more of it but it does ultimately have limits. In particular, the deeper the mines go the more costly it gets. Plus there's a lot of coal that realistically nobody's going to want to mine.
In the Australian context well there's technically mineable coal within the metropolitan areas of Sydney, Melbourne and Hobart, there's coal west of Brisbane and in Adelaide's case there's coal under the CBD itself at the northern end and it stretches under the Torrens River up toward North Adelaide. So within that area is the heart of the commercial district, a good portion of all Adelaide hotels, state parliament, the Oval, the zoo, the Royal Adelaide Hospital, railway station, university, a golf course, etc. Chance anyone's going to mine that I think we can safely say is zero.
Here's a quote from Tasmania over 40 years ago:
That was written about 5 years before mainstream media first reported on what was then termed "the greenhouse effect" now known as climate change.
It's referring to a number of individually small hydro schemes in Tasmania that have been identified as technically practical to build but never actually built and which have never seen a serious proposal to build them, although detailed investigations were done in the past to confirm viability. Note the 285 MW is average output, constant 24/365, and is not a peak power value which would be considerably higher. That list doesn't include the more well known unbuilt schemes subject to past controversy in the south-west.
Now I'll readily acknowledge there's a legitimate case against some hydro developments on environmental grounds, anything that wipes out a species is too high a price to pay for keeping the lights on, but on the other hand fossil fuels have very real, undeniable problems far beyond just climate change. Oil and gas are physically quite limited whilst coal comes with all the issues of digging up the land, ash to dispose of, etc.
Plus it must be said oil, gas and war are never too far from each other. Another reason to not like them.
So there's a lot of reasons to want to minimise the use of fossil fuels even without saying a word about climate. They're problematic full stop.